A recording device formed as a thermal printer is known from DE-PS 32 02 185. Such a recording device demonstrates a high peak power requirement during the recording process. To cover this peak power requirement, providing a corresponding high-performance power pack is possible. However, such a high-performance component would significantly increase the overall costs of the recording device. If accumulators, which are perfectly capable of giving off large amounts of power for a short time, are used in the known thermal printer as a power source, the number of possible recording processes is limited by the lifetime (i.e. the capacity) of the accumulators. To maintain uniform printing quality with a decreasing performance capacity of the accumulators, the printing parameters must be adapted. Such an adaptation takes place in the thermal printer known from DE-PS 32 02 185 during the period when its heating elements are kept on. However, doing so has a disadvantageous effect on the printing speed.
When using rechargeable accumulators, a discharge beyond a certain charge state (i.e. complete discharge or deep discharge) must also be avoided, otherwise damage or destruction of these accumulators may result. The lifetime, which is limited by the number of charging cycles and the useful capacity of the accumulators, is determined to a significant extent by the discharge speed. Therefore, in a recording device powered by rechargeable accumulators, efficient use of small amounts of power is necessary for reasons of economic efficiency and recording capacity.
The present invention is therefore based on the task of creating a method for operating a recording device powered by at least one rechargeable accumulator wherein the greatest possible number of recording processes can be carried out and wherein deep discharge of the rechargeable accumulators is reliably avoided.